JP5711714B2 - Electronics - Google Patents

Description

The present invention relates to an electronic device and an electronic system having a circuit including transistors. For example, the present invention relates to an electronic apparatus in which an electro-optical device typified by a liquid crystal display panel is mounted as a component.

In recent years, development of display devices such as electronic books has been actively promoted. In particular, a technique for displaying an image using a display element having a memory property greatly contributes to reduction of power consumption, and therefore is actively developed (Patent Document 1).

In addition, a display device equipped with a touch sensor has attracted attention. A display device equipped with a touch sensor is called a touch panel or a touch screen (hereinafter, this is also simply referred to as “touch panel”). Also, Patent Document 2 discloses a display device equipped with an optical touch sensor.

JP 2006-267982 A JP 2001-292276 A

It is an object to provide an electronic device that is improved in impact resistance, weight-reduced, and flexible by using a flexible film as a base instead of a hard substrate such as a glass substrate.

Another object is to configure a driver circuit that is advantageous for energy saving of electronic devices such as portable information terminals with limited power.

In addition, the user can input information by browsing the information at any place, touching the keyboard displayed on the screen directly, or indirectly using a stylus pen, etc.
Another object is to provide a new electronic device that can use the input information.
Pixel configuration that increases the light receiving area of the photosensor and the pixel electrode area per unit area in order to realize an electronic device that allows users to input information by browsing information and touching a keyboard displayed on the screen Is also an issue.

Another object is to provide a new electronic device that realizes both a still image mode such as a keyboard display and a moving image mode on one screen.

In still image mode, after displaying a still image in a part of a certain display area, power supply to the display element in that display area is stopped and the still image remains visible for a long time. One of the issues is to reduce power consumption by maintaining it.

In an electronic device having a display unit that displays an image using external light, the display unit has a touch input function using a photosensor, and a keyboard button is displayed on at least a part of the display unit. Information is input by touching a desired key, and a display corresponding to the desired key is displayed on the display unit.

The photosensor detects external light incident on the display unit, and detects a local shadow of external light that occurs when the user points to a desired position of the display unit with a fingertip. The input processing unit processes the position on the display unit of the photosensor that detects the local shadow of the external light as the touch input coordinate position. Data corresponding to the touch input coordinate position, that is, key information is output as image data to the display unit by the video signal processing unit.

In addition, during the period when the user is inputting using the keyboard displayed on the display unit, the first display area displaying the keyboard displays a still image and is touched during input. A moving image is displayed in the second display area during a period in which characters or numbers corresponding to the keys are written one after another or during a period in which characters are converted.

One embodiment of the present invention disclosed in this specification is an electronic device including a video signal processing unit that switches a first screen region of a display unit to a screen region for touch input or a screen region for output display. The electronic device also includes a video signal processing unit that supplies different signals to the display element of the display unit depending on whether the image displayed on the display unit is a still image or a moving image. Power consumption can be saved by deactivating the display element control circuit after writing. In particular, a decoder circuit is preferably used as the scan line driver circuit.

In addition, a switching transistor included in a conventional active matrix display device has a large off-state current, and there is a problem in that a signal written to a pixel leaks through the transistor and disappears even in an off state. In one embodiment of the present invention, a transistor including an oxide semiconductor layer is used as a switching transistor, whereby an extremely low off-state current, specifically, an off-current density per channel width of 1 μm is 10 aA (1 × 10 ⁻¹⁷ at room temperature).
A / μm) or less, further, 1 aA (1 × 10 ⁻¹⁸ A / μm) or less, further 10 zA (1 × 10 ⁻²⁰ A / μm) or less, and the pixel has an image signal or the like. The holding time of the electric signal can be increased and the writing interval can be set longer. Therefore, by using a transistor including an oxide semiconductor layer, power consumption can be further saved by extending the period during which the display element control circuit is not operated after writing a still image.

Another aspect of the invention relating to a device that realizes the electrical device is an electronic device including a display unit having a touch input function, and is a first electrode that is electrically connected to a reflective electrode that is a pixel electrode on a flexible substrate. The photosensor includes a photodiode, a second transistor having a gate signal line electrically connected to the photodiode, and a third transistor. One of the source and the drain of the transistor is electrically connected to the photosensor reference signal line, the other of the source and the drain is electrically connected to one of the source and the drain of the third transistor, and the source of the third transistor Alternatively, the other of the drains is electrically connected to the photosensor output signal line.

The above configuration solves at least one of the above problems.

In the above structure, the oxide semiconductor layer of the second transistor overlaps with the readout signal line through the gate insulating layer, and the readout signal line overlaps with the reflective electrode which is a pixel electrode. By adopting a pixel configuration in which a readout signal line and a third transistor are arranged below the reflective electrode, the light receiving area and the pixel electrode area (hereinafter referred to as the reflective electrode area) per unit area are efficiently obtained. Can be used well.

Another aspect of the invention is an electronic device including a display unit having a touch input function, a first transistor electrically connected to the first reflective electrode on the flexible substrate, and a second reflective electrode. A second transistor electrically connected to the photosensor, and the photosensor,
A third diode having a photodiode and a gate signal line electrically connected to the photodiode;
And the fourth transistor, one of the source and drain of the third transistor is electrically connected to the photosensor reference signal line, and the other of the source and drain is the source or drain of the fourth transistor. The other of the source and the drain of the fourth transistor is electrically connected to the photosensor output signal line, and the oxide semiconductor layer of the fourth transistor overlaps with the first reflective electrode The photo sensor reference signal line is
An electronic device is characterized by overlapping with a second reflective electrode.

In the above configuration, when the pixel structure is viewed from above, the light receiving area of one photosensor is designed to be arranged between the two reflecting electrodes, and the light receiving area and the reflecting electrode area of the photosensor per unit area are designed. Can be used efficiently.

In the above structure, the oxide semiconductor layer of the third transistor overlaps with the read signal line through the gate insulating layer, and the read signal line overlaps with the first reflective electrode. By adopting a pixel configuration in which a readout signal line and a fourth transistor are arranged below the first reflective electrode,
The light receiving area of the photosensor and the reflective electrode area per unit area can be used efficiently.

In the above structure, one of the source and the drain of the fourth transistor overlaps with the first reflective electrode, and the other of the source and the drain of the fourth transistor overlaps with the second reflective electrode. With such a pixel configuration, the light receiving area and the reflective electrode area of the photosensor per unit area can be efficiently used.

In the above structure, a color filter is provided at a position overlapping the first reflective electrode or the second reflective electrode, so that full color display can be performed.

Further, by using a reflective liquid crystal display device, display contents can be visually recognized if there is external light such as sunlight or illumination light even without a backlight, which is advantageous for energy saving.

A portable information terminal that displays moving images and still images within one screen can be realized, and different screens and still image display screens for moving images and still images are displayed. Reduce power consumption. Further, since the liquid crystal display device is a reflective liquid crystal display device, halftone display can be performed in a wider range than the electrophoretic display device.

In addition, the user can use a portable information terminal that has been reduced in weight by using a flexible substrate, browse information regardless of location, and touch-input on a keyboard displayed on the screen.
The input result can be displayed on the same screen displaying the keyboard.

1 is an external view illustrating one embodiment of the present invention. FIG. 10 is a block diagram illustrating one embodiment of the present invention. FIG. 6 is an equivalent circuit diagram of a pixel illustrating one embodiment of the present invention. 1 is a schematic diagram of a photosensor driving circuit according to one embodiment of the present invention. 3 is a timing chart illustrating one embodiment of the present invention. 1 is an example of a pixel plan view illustrating one embodiment of the present invention. FIG. 3 is an example of a plan view illustrating a positional relationship between a reflective electrode and a black matrix, illustrating one embodiment of the present invention. 1 is an example of a cross-sectional view of a pixel illustrating one embodiment of the present invention. 1 is a schematic diagram of a liquid crystal display module illustrating one embodiment of the present invention. 4A and 4B are an external view and a block diagram of a display device which is one embodiment of the present invention. It is the cross-sectional photograph of a part of photodiode, and its schematic diagram. It is a photograph which shows the mode of the display image displayed on the display panel. 1 is an example of a cross-sectional view of a pixel illustrating one embodiment of the present invention. 1 is a schematic diagram of an electronic book illustrating one embodiment of the present invention. FIG. 10 is a block diagram of a driver circuit illustrating one embodiment of the present invention. It is a figure which shows the time relationship of the signal of each data line. It is a circuit diagram which comprises the inside of a block. It is a figure which shows time and the electric potential of each node.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it will be easily understood by those skilled in the art that modes and details can be variously changed. In addition, the present invention is not construed as being limited to the description of the embodiments below.

(Embodiment 1)
In this embodiment, an example of an electronic device having a display portion that performs image display using external light is illustrated in FIG.
Shown in (A) and FIG.

A display portion 1032 of the electronic device 1030 has a touch input function using a photosensor.
As shown in (A), a plurality of keyboard buttons 1031 are displayed in the display area 1033. The display portion 1032 indicates the entire display area and includes a display portion area 1033. Then, the user touches and inputs a desired keyboard button, and the display unit 1032 displays the input result.

Since the display area 1033 displays a still image, power consumption can be saved by disabling the display element control circuit during a period other than writing.

An example of a state in which the electronic device 1030 is used is shown. For example, the keyboard buttons displayed in the area 1033 of the display unit are sequentially touched with a user's finger or non-contact character input is performed, and the resulting text is displayed in an area other than the area 1033 of the display unit. indicate. When the user removes his / her finger from the keyboard of the screen and the period during which the output signal of the photo sensor is not detected passes for a certain period of time, the keyboard display displayed in the display area 1033 is automatically turned off,
The input text is also displayed in the area 1033 of the display unit, and the user can check the text input to the full screen. When inputting again, the display unit 1032 is touched with a finger of the user, or the output signal of the photo sensor is detected in a non-contact manner so that the keyboard button is displayed again in the area 1033 of the display unit, and character input is performed. It can be carried out.

Further, instead of automatically, the user can press the changeover switch 1034 to eliminate the keyboard display, and the entire display unit 1032 can be a still image as shown in FIG. Even if the power switch 1035 is pressed to turn off the power, the still image can be maintained for a long time. Further, the keyboard can be displayed by pressing the keyboard display switch 1036 so that touch input is possible.

The changeover switch 1034, the power switch 1035, and the keyboard display switch 1036 may be displayed as switch buttons on the display portion 1032 and may be operated by touching the displayed switch buttons.

Further, the display area 1033 is not limited to displaying a still image, and may display a moving image temporarily or partially. For example, the display position of the keyboard button is temporarily changed according to the user's preference, or the display change is partially applied only to the corresponding keyboard button so that it can be known whether or not the input has been made when inputting without contact. May be given.

In addition, the electronic device 1030 includes at least a battery, a memory (Flash Memory circuit, SRAM circuit, DRAM circuit, etc.) for storing data information, a CPU (
A configuration including a central processing circuit and a logic circuit is preferable. By providing the CPU and memory, various software can be installed, and some or all of the functions of the personal computer can be provided.

In addition, a tilt detection unit such as a gyroscope or a three-axis acceleration sensor is provided for the electronic device 1030, and functions used in the electronic device 1030 according to a signal from the tilt detection unit, particularly display on the display unit and Functions related to input can be switched by an arithmetic circuit. Therefore, unlike the case where the type, size, or arrangement of the input keys is predetermined as in the case of the provided operation keys, the convenience for the user can be improved.

Next, an example of a display panel included in the display portion 1032 will be described with reference to FIG. The display panel 100 includes a pixel circuit 101, a display element control circuit, and a photosensor control circuit. The pixel circuit 101 includes a plurality of pixels 103 and 10 arranged in a matrix in the matrix direction.
4 and a photo sensor 106. The pixels 104 and 103 each have one display element. In this embodiment, one photosensor 106 is provided between the pixel 103 and the pixel 104.
In this example, the number of photosensors is half the number of pixels. However, the present invention is not particularly limited, and each pixel has one photosensor so that the number of photosensors is the same as the number of pixels. The number of photosensors may be one third of the number of pixels.

The display element 105 includes a transistor, a storage capacitor, a liquid crystal element having a liquid crystal layer, and the like. The transistor has a function of controlling charge injection into the storage capacitor or discharge of charge from the storage capacitor. The storage capacitor has a function of holding a charge corresponding to a voltage applied to the liquid crystal layer. Image display is realized by making light and darkness (gradation) of light transmitted through the liquid crystal layer by utilizing the fact that the polarization direction is changed by applying a voltage to the liquid crystal layer. For light passing through the liquid crystal layer,
Light emitted from the surface of the liquid crystal display device using external light (sunlight or illumination light) is used.
The liquid crystal layer is not particularly limited, and a known liquid crystal material (typically a nematic liquid crystal material or a cholesteric liquid crystal material) may be used. For example, polymer dispersed liquid crystal (PDLC (Po
lymer Dispersed Liquid Crystal), polymer dispersed liquid crystal,
Polymer dispersion type liquid crystal) or polymer network type liquid crystal (PNLC (Polyme
r Network Liquid Crystal)) may be used for the liquid crystal layer, and white display (bright display) may be performed using light scattered by the liquid crystal. When PDLC or PNLC is used for the liquid crystal layer, a polarizing plate is not required, and a display close to the paper surface can be realized, which is gentle to the user's eyes and can reduce fatigue.

The display element control circuit is a circuit for controlling the display element 105, and displays a signal input to the display element 105 through a signal line (also referred to as a “source signal line”) such as a video data signal line. It includes an element driver circuit 107 and a display element driver circuit 108 for inputting a signal to the display element 105 through a scanning line (also referred to as a “gate signal line”).

For example, the display element driver circuit 108 on the scan line side has a function of selecting display elements included in pixels arranged in a specific row. The display element driver circuit 107 on the signal line side has a function of applying an arbitrary potential to the display element included in the pixel in the selected row. Note that in a display element to which a high potential is applied by the display element driver circuit 108 on the scanning line side, the transistor is turned on, and the charge supplied from the display element driver circuit 107 on the signal line side is supplied.

The photosensor 106 includes a light receiving element such as a photodiode, which has a function of generating an electric signal by receiving light, and a transistor.

The photo sensor control circuit is a circuit for controlling the photo sensor 106, and is a photo sensor readout circuit 10 on the signal line side such as a photo sensor output signal line and a photo sensor reference signal line.
9 and a photo sensor driving circuit 110 on the scanning line side. The photo sensor driving circuit 110 on the scanning line side has a function of performing a reset operation and a selection operation, which will be described later, on the photo sensors 106 included in the pixels arranged in a specific row. Further, the photosensor reading circuit 109 on the signal line side has a function of taking out an output signal of the photosensor 106 included in the pixel in the selected row.

In this embodiment, circuit diagrams of the pixel 103, the photosensor 106, and the pixel 104 are described with reference to FIGS. The pixel 103 includes a display element 105 including a transistor 201, a storage capacitor 202, and a liquid crystal element 203. In addition, the photosensor 106 includes a photodiode 204, a transistor 205, and a transistor 206. In addition, the pixel 104
Includes a transistor 221, a storage capacitor 222, and a display element 125 including a liquid crystal element 223.

In the transistor 201, the gate is electrically connected to the gate signal line 207, one of the source and the drain is electrically connected to the video data signal line 210, and the other of the source and the drain is electrically connected to one electrode of the storage capacitor 202 and one electrode of the liquid crystal element 203. It is connected. The other electrode of the storage capacitor 202 is electrically connected to the capacitor wiring 214 and is kept at a constant potential. Liquid crystal element 2
The other electrode of 03 is kept at a constant potential. The liquid crystal element 203 is an element including a pair of electrodes and a liquid crystal layer between the pair of electrodes.

When “H” (high potential) is applied to the gate signal line 207, the transistor 201 applies the potential of the video data signal line 210 to the storage capacitor 202 and the liquid crystal element 203. The storage capacitor 202 holds the applied potential. The liquid crystal element 203 changes the light transmittance according to the applied potential.

One electrode of the photodiode 204 is connected to the photodiode reset signal line 208.
The other electrode is electrically connected to the gate of the transistor 205. Transistor 20
5, one of the source and the drain is electrically connected to the photosensor reference signal line 212, and the other of the source and the drain is electrically connected to one of the source and the drain of the transistor 206.
The transistor 206 has a gate electrically connected to the read signal line 209 and the other of the source and the drain electrically connected to the photosensor output signal line 211.

The transistor 221 has a gate electrically connected to the gate signal line 227, one of the source and the drain electrically connected to the video data signal line 210, and the other of the source and the drain electrically connected to one electrode of the storage capacitor 222 and one electrode of the liquid crystal element 223. Connected. The other electrode of the storage capacitor 222 is electrically connected to the capacitor wiring 224 and is kept at a constant potential. The other electrode of the liquid crystal element 223 is kept at a constant potential. The liquid crystal element 223 includes a pair of electrodes,
An element including a liquid crystal layer between the pair of electrodes.

Next, an example of a configuration of the photosensor reading circuit 109 will be described with reference to FIGS. As an example, the display unit includes 1024 rows and 768 columns of pixels, and one display element is provided for each pixel in each row, and a photosensor is provided between two rows and columns. That is, the display element has 1024 rows and 768 columns, and the photosensor has 512 rows and 768 columns. In addition, an example in which the photosensor output signal lines are output to the outside of the display device as a set of two rows is shown.
That is, one output is obtained from two photosensors sandwiched between four pixels in 2 rows and 2 columns.

FIG. 3 shows two pixels for two rows and one column and one photosensor in the circuit configuration of the pixel. One display element is provided per pixel, and one photosensor is provided between two pixels. FIG. 4 shows a circuit configuration of the photosensor readout circuit 109, and some photosensors are also shown for explanation.

As shown in FIG. 4, the scanning line driving circuit of the photosensor simultaneously drives four rows of pixels (that is, two rows of photosensors) and shifts the selected row by one photosensor row corresponding to two rows of pixels. Consider an example of performing a driving method. Here, the photosensors in each row are continuously selected during a period in which the scanning line driver circuit shifts the selected row twice. By using such a driving method, it becomes easy to improve the frame frequency of imaging by the photosensor. In particular, it is advantageous in the case of a large display device. The output signal line 21 of the photosensor
1, the outputs of the photosensors for two rows are superimposed at the same time. Further, by repeating the shift of the selected row 512 times, all the photosensors can be driven.

As shown in FIG. 4, the photosensor readout circuit 109 has one selector for each column of 24 pixels. The selector selects one set from 12 sets of two columns for the output signal line 211 of the photosensor in the display unit, and acquires the output. That is, the entire photosensor readout circuit 109 has 32 selectors and simultaneously obtains 32 outputs. A total of 384 outputs corresponding to one row of photosensors can be acquired by performing selection by all selectors for all 12 sets. By selecting 12 sets by the selector each time the scanning line driving circuit of the photosensor shifts the selected row, the output of all the photosensors can be obtained.

In this embodiment mode, as illustrated in FIG. 4, the photosensor readout circuit 109 on the signal line side includes:
Consider a configuration in which an output of a photosensor that is an analog signal is taken out of a display device, amplified using an amplifier provided outside the display device, and then converted into a digital signal using an AD converter. Of course, an AD converter may be mounted on the same substrate as the display device so that the output of the photosensor is converted into a digital signal and then taken out of the display device.

The operation of each photosensor is realized by repeating the reset operation, the accumulation operation, and the selection operation. The reset operation is an operation in which the potential of the photodiode reset signal line 208 is set to “H”. When the reset operation is performed, the photodiode 204 becomes conductive, and the potential of the gate signal line 213 to which the gate of the transistor 205 is connected becomes “H”.

The cumulative operation is an operation of setting the potential of the photodiode reset signal line 208 to “L” (Low potential) after the reset operation. The selection operation is an operation for setting the potential of the read signal line 209 to “H” after the accumulation operation.

During the accumulation operation, the stronger the light applied to the photodiode 204, the lower the potential of the gate signal line 213 to which the gate of the transistor 205 is connected, and the channel resistance of the transistor 205 increases. Therefore, during the selection operation, a current flowing through the photosensor output signal line 211 via the transistor 206 is reduced. On the other hand, during the cumulative operation, the photodiode 20
4, the light that irradiates the photosensor output signal line 211 via the transistor 206 increases during the selection operation as the light applied to 4 is weaker.

In the present embodiment, local shadows of external light can be detected by executing the reset operation, cumulative operation, and selection operation of all photosensors. In addition, by appropriately performing image processing or the like on the detected shadow, it is possible to know the position where the finger, the stylus pen, or the like has contacted the display device. If an operation corresponding to the touched position, for example, character input is specified, a character type can be specified to input a desired character.

Note that in the display device in this embodiment, a local shadow of external light is detected by a photosensor. Therefore, even if a finger, a stylus pen, or the like is not in physical contact with the display device, detection is possible if a shadow is formed by proximity without contact. Hereinafter, contact of a finger, a stylus pen, or the like with a display device includes non-contact proximity.

With the above structure, the display portion 1032 can have a touch input function.

When touch input is performed, an image including a still image such as a keyboard is displayed, and input is performed by touching a desired character position on the displayed keyboard with a finger or a stylus pen. When a display device is used, operability is improved. When realizing such a display device, the power consumption in the display device can be significantly reduced as follows. That is, for the first screen area that displays a still image on the display unit, after displaying the still image, the supply of power to the display element in the area is stopped and the still image can be visually recognized thereafter. It is effective to maintain for a long time. And about the remaining 2nd screen area | region of a display part, the input result by touch input is displayed, for example. It is possible to save power by disabling the display element control circuit during a period other than when the display image in the second screen area is updated. A driving method that enables such control will be described below.

For example, in a display device having a display unit in which display elements are arranged in 1024 rows and 768 columns,
FIG. 5 shows a timing chart of the shift register of the scan line driver circuit. A period 61 in FIG. 5 is one cycle period (64.8 μsec) of the clock signal, and a period 62 is a period required to write from the first row to the 512th row of the display element corresponding to the second screen area (8. 36
msec), and the period 63 corresponds to one frame period (16.7 msec).

Here, the shift register of the scan line driver circuit is a four-phase clock type shift register that operates with the first clock signal CK1 to the fourth clock signal CK4. The first clock signal CK1 to the fourth clock signal CK4 are signals that are shifted from each other by a quarter period. When the start pulse signal GSP is “H”, the gate signal lines G1 to G5 in the first row
The gate signal line G512 in the twelfth row sequentially becomes “H” while being delayed by a quarter period. Each gate signal line is set to “H” for a half cycle period, and the gate signal lines in successive rows are simultaneously set to “H” for a quarter cycle period.

Here, the display elements in each row are continuously selected during a period in which the scanning line driver circuit shifts the selected row twice. The display image can be updated by inputting the display image data in the latter half of the period when the display element in the row is selected.

Here, the display element control circuit is not operated during the period excluding the period for updating the display image from the first row to the 512th row of the display elements corresponding to the second screen region. That is, the display image is not updated from line 513 to line 1024 of the display element corresponding to the first screen area.
The display element control circuit is not operated.

In order to deactivate the display element control circuit, the clock signal is stopped ("L" as shown in FIG. 5).
It is also effective to stop the supply of the power supply voltage at the same time.

Further, during a period when the display element corresponding to the second screen area is not selected, that is, during a period when the display image is not updated, the source side driver circuit may similarly stop the clock signal and the start pulse signal. . This can save further power.

Further, power can be saved by using a decoder instead of the shift register of the scanning line driver circuit.

(Embodiment 2)
In this embodiment mode, a pixel structure corresponding to FIGS. 2 and 3 described in Embodiment Mode 1 will be described below with reference to FIGS. 6, 7, and 8 are described using the same reference numerals in the same portions as those in FIGS. 2 and 3.

FIG. 6 is an example of a pixel plan view corresponding to the circuit diagram of FIG. FIG. 8A shows a state before forming the electrode of the photodiode. Note that a cross-sectional view taken along a chain line AB in FIG. 6 and a cross-sectional view taken along a chain line CD correspond to FIG. 8A, respectively.

First, after a conductive film is formed over the substrate 230, gate signal lines 207, 213, and 227, a capacitor wiring 224, a photodiode reset signal line 208, and readout are performed by a first photolithography process using a first exposure mask. Signal line 209, photo sensor reference signal line 21
2 is formed. In this embodiment, a glass substrate is used as the substrate 230.

An insulating film serving as a base film may be provided between the substrate 230 and the conductive film. The base film is the substrate 230.
And has a function of preventing diffusion of an impurity element from the substrate, and can be formed using a stacked structure of one or more films selected from a silicon nitride film, a silicon oxide film, a silicon nitride oxide film, and a silicon oxynitride film.

The conductive film can be formed as a single layer or a stacked layer using a metal material such as molybdenum, titanium, tantalum, tungsten, aluminum, copper, neodymium, or scandium, or an alloy material containing any of these as a main component. .

Next, an insulating layer covering these wirings is formed, and selectively etched by leaving the insulating layer 231 only in a portion intersecting with a wiring to be formed later by a second photolithography process using a second exposure mask. I do. In this embodiment, the insulating layer 231 is formed using a silicon oxynitride film with a thickness of 600 nm.

Next, a gate insulating layer 232 and an oxide semiconductor film are formed, and the gate signal line 207 is interposed through the gate insulating layer 232 by a third photolithography process using a third exposure mask.
213, 227 and the read signal line 209, the first oxide semiconductor layer 23 which overlaps with each other
3. A second oxide semiconductor layer 253, a third oxide semiconductor layer 255, and a fourth oxide semiconductor layer 256 are formed. In this embodiment, a silicon oxynitride film with a thickness of 100 nm is used as the gate insulating layer 232, and an In—Ga—Zn—O film with a thickness of 30 nm is used as the oxide semiconductor film.

The first oxide semiconductor layer 233, the second oxide semiconductor layer 253, the third oxide semiconductor layer 255, and the fourth oxide semiconductor layer 256 have a chemical formula of InMO ₃ (ZnO) _m (m> 0
) Can be used. Here, M represents one or more metal elements selected from Ga, Al, Mn, and Co. For example, as M, Ga, Ga and A
l, Ga and Mn, or Ga and Co. Further, the oxide thin film may contain SiO ₂ .

In addition, as a target for producing an oxide thin film by a sputtering method, for example, an oxide target having a composition ratio of In ₂ O ₃ : Ga ₂ O ₃ : ZnO = 1: 1: 1 [molar ratio] is used. An In—Ga—Zn—O film is formed. Without limitation to the material and the composition of the target, for _{example, In 2 O 3: Ga 2} O 3: ZnO = 1: 1: 2 [mol ratio]
The oxide target may be used. Note that here, for example, an In—Ga—Zn—O film means an oxide film containing indium (In), gallium (Ga), and zinc (Zn), and the stoichiometric ratio is particularly high. It doesn't matter.

Next, first heat treatment is performed on the oxide semiconductor layer. Through the first heat treatment, the oxide semiconductor layer can be dehydrated or dehydrogenated. The temperature of the first heat treatment is 400 ° C.
The temperature is 750 ° C. or lower, or 400 ° C. or higher and lower than the strain point of the substrate. In this embodiment, R
650 in a nitrogen atmosphere using a TA (Rapid Thermal Anneal) apparatus.
After performing the heat treatment at 6 ° C. for 6 minutes, the substrate is introduced into an electric furnace which is one of the heat treatment devices without being exposed to the atmosphere, and the oxide semiconductor layer is subjected to 1 hour at 450 ° C. in a nitrogen atmosphere After the heat treatment, the oxide semiconductor layer is moved to the oxide semiconductor layer deposition chamber so as not to be exposed to the air to prevent re-mixing of water and hydrogen into the oxide semiconductor layer, whereby the oxide semiconductor layer is obtained.

Next, in a fourth photolithography process using a fourth exposure mask, the gate insulating layer 232 is selectively removed to form an opening reaching the gate signal line 213 and an opening reaching the photodiode reset signal line 208. To do.

Next, a conductive film is formed over the gate insulating layer 232 and the oxide semiconductor layer. As the conductive film, for example, a metal film containing an element selected from Al, Cr, Cu, Ta, Ti, Mo, W, or an alloy film containing a nitride of the above element as a component, or the above element It is possible to use an alloy film combining the above. In this embodiment mode, the conductive film has a three-layer structure of a Ti film with a thickness of 100 nm, an Al film with a thickness of 400 nm, and a Ti film with a thickness of 100 nm. Then, a resist mask is formed over the conductive film by a fifth photolithography process using the fifth exposure mask, and selective etching is performed, so that the video data signal line 210, the photosensor output signal line 211, and the electrode layer are formed. 234, 235, 254, 257, 258, 259 are formed.

Note that the transistor 221 in FIG. 3 includes the first oxide semiconductor layer 2 as illustrated in FIG.
33, and the electrode layer 234 is a source electrode layer or a drain electrode layer. 6 and 8A, the electrode layer 234 uses the gate insulating layer 232 as a dielectric, and forms a capacitor wiring 224 and a storage capacitor 222. As illustrated in FIG. 6, the transistor 201 is a transistor including the second oxide semiconductor layer 253 and using the electrode layer 254 as a source electrode layer or a drain electrode layer.

In FIG. 3, the transistor 206 which is one element included in the photosensor 106 includes a third oxide semiconductor layer 255 as illustrated in FIG. 6, and the electrode layer 257 is a source electrode layer or a drain electrode layer. It is a transistor. In addition, as illustrated in FIG. 6, the transistor 205 includes a fourth oxide semiconductor layer 256 and uses the electrode layer 257 or the electrode layer 258 as a source electrode layer or a drain electrode layer. As shown in FIG. 8A, the gate signal line 213 of the transistor 205 is connected to the gate insulating layer 232 through the opening.
The electrode layer 236 is electrically connected.

Next, a second heat treatment (preferably 2) is performed in an inert gas atmosphere or an oxygen gas atmosphere.
00 ° C to 400 ° C, for example, 250 ° C to 350 ° C). In this embodiment, second heat treatment is performed at 300 ° C. for one hour in a nitrogen atmosphere. When the second heat treatment is performed,
Heat is applied in a state where part of the oxide semiconductor layer (channel formation region) is in contact with the insulating layer.

Next, an insulating layer 237 to be a protective insulating layer is formed, and an opening reaching the electrode layer 235, an opening reaching the electrode layer 234, and an opening reaching the electrode layer 236 are formed by a sixth photolithography process using a sixth exposure mask. Form. In this embodiment, a 300-nm-thick silicon oxide film obtained by a sputtering method is used for the insulating layer 237.

Next, a p-layer 238, an i-layer 239, and an n-layer 240 are stacked by plasma CVD. In this embodiment, a microcrystalline silicon film containing boron with a thickness of 60 nm is used as the p layer 238, an amorphous silicon film with a thickness of 400 nm is used as the i layer 239, and the n layer 24
A microcrystalline silicon film containing phosphorus with a thickness of 80 nm is used as 0. Then, after selectively etching the p layer 238, the i layer 239, and the n layer 240 by the seventh photolithography process using the seventh exposure mask, the n layer is further removed as shown in FIG. The peripheral portion of 240 and a part of the i layer 239 are selectively removed. A cross-sectional view up to this stage is FIG.
The plan view corresponds to FIG.

Next, a photosensitive organic resin layer is formed, and the region that becomes the opening is exposed with the eighth exposure mask, the region that becomes uneven with the ninth exposure mask is exposed, developed, and partially insulated with insulation. Layer 241
An eighth photolithography process for forming the film is performed. In this embodiment, an acrylic resin is used as the photosensitive organic resin layer, and the film thickness is 1.5 μm.

Next, a reflective conductive film is formed, and a reflective electrode layer 242 and a connection electrode layer 243 are formed by a ninth photolithography process using a tenth exposure mask. Note that the reflective electrode layer 242 and the connection electrode layer 243 are illustrated in FIG. As the conductive film having reflectivity, Al,
Ag or an alloy thereof such as aluminum containing Nd or an Ag—Pd—Cu alloy is used. In this embodiment mode, the reflective conductive film uses a stack of a 100 nm-thick Ti film and a 300 nm-thick Al film provided thereover. Then, after the ninth photolithography step, third heat treatment is performed in this embodiment mode at 250 ° C. for one hour in a nitrogen atmosphere.

Through the above process, a transistor electrically connected to the reflective electrode layer 242 over the same substrate;
The photodiode electrically connected to the gate signal line 213 through the connection electrode layer 243 can be manufactured by nine photolithography processes using a total of ten exposure masks.

Note that a cross-sectional photograph of the periphery of the photodiode is shown in FIG. In FIG. 11A,
A cross section of the photodiode 204 is shown, and a schematic cross section thereof is shown in FIG.

Then, an alignment film 244 that covers the reflective electrode layer 242 is formed. A cross-sectional view at this stage is shown in FIG.
It corresponds to B). Note that the same reference numerals are used for common portions in FIGS. 8B and 11B. Thus, an active matrix substrate can be manufactured.

Then, a counter substrate to be bonded to the active matrix substrate is prepared. A light-shielding layer (also referred to as a black matrix) and a light-transmitting conductive film are formed over the counter substrate, and columnar spacers using an organic resin are formed. Finally, it is covered with an alignment film.

This counter substrate is bonded to the active matrix substrate using a sealant, and a liquid crystal layer is sandwiched between the pair of substrates. The light shielding layer of the counter substrate is provided so as not to overlap the display area of the reflective electrode layer 242 and the sensing area of the photodiode. The columnar spacer provided on the counter substrate is aligned so as to overlap with the electrode layers 251 and 252. The columnar spacer keeps the distance between the pair of substrates constant by overlapping with the electrode layers 251 and 252. Electrode layer 2
Since 51 and 252 can be formed in the same step as the electrode layer 234, they can be provided without increasing the number of masks. The electrode layers 251 and 252 are not electrically connected anywhere and are in a floating state.

A plan view of a pixel in the pair of substrates thus bonded corresponds to FIG. In FIG. 7, regions that do not overlap with the black matrix are a light receiving region and a reflective electrode region of the photosensor. In one unit area (120 μm × 240 μm) shown in FIG. 7, the ratio of the area of the reflective electrode is 77.8%, and the light receiving area of the photosensor is about 1140 μm ² . Moreover, since the reflective electrode layer 242 is provided on the photosensitive organic resin layer having irregularities,
It has a random plane pattern as shown in FIG. Reflecting the surface shape of the photosensitive organic resin layer, the surface of the reflective electrode layer 242 is also provided with irregularities to prevent specular reflection. In FIG. 7, the concave portion 245 of the reflective electrode layer 242 is also shown. The peripheral edge of the concave portion 245 is located inside the peripheral edge of the reflective electrode layer, and the photosensitive organic resin layer below the concave portion 245 is from other regions. The film thickness is also thin.

In addition, if necessary, a phase difference film for adjusting the phase difference, a film having a polarizing function, an antireflection plate, an optical film such as a color filter, etc. are provided on the surface of the counter substrate where the external light is incident. May be.

Further, FIG. 12 shows a photograph in which a display is photographed by inputting a video signal through an FPC to an actually manufactured panel. Half of the panel screen was displayed as a still image and the other half as a video. Half of the screen of the panel is displayed as a still image and the other half is displayed as a moving image, so that power consumption can be reduced. In addition, by touching the screen with a finger, a keyboard button is displayed as shown in FIG. 1A. By touching the displayed keyboard button with a finger, information is input, and the display area corresponds to the keyboard button. Can be displayed. Also,
If a photo sensor is used and the fingertip is close to the screen and the finger does not touch the screen, there is enough external light and the finger shadow can be sensed. You can also.

(Embodiment 3)
In this embodiment, an example of a liquid crystal display module provided with a color filter and capable of full color display is described.

FIG. 9 shows the configuration of the liquid crystal display module 190. The liquid crystal display module 190 includes a display panel 120 in which liquid crystal elements are provided in a matrix, and a polarizing plate and a color filter 115 overlapping the display panel 120. Further, FPCs (flexible printed circuits) 116 a and 116 b serving as external input terminals are electrically connected to terminal portions provided on the display panel 120. Display panel 120 has the same configuration as display panel 100 of the first embodiment.
However, since it is a case of full color display, a circuit configuration that uses three display elements of a red display element, a green display element, and a blue display element, and supplies different video signals to each of them.

FIG. 9 schematically shows a state in which the external light 139 is transmitted through the liquid crystal element on the display panel 120 and reflected by the reflective electrode. For example, in a pixel that overlaps with the red region of the color filter, the external light 139 passes through the color filter 115, then passes through the liquid crystal layer, is reflected by the reflective electrode, passes through the color filter 115 again, and is extracted as red light. . In FIG.
Three colors of light 135 are schematically indicated by arrows (R, G, and B). Since the intensity of the light transmitted through the liquid crystal element is modulated by the image signal, the observer can capture an image with the reflected light of the external light 139.

The display panel 120 includes a photo sensor and has a touch input function. It is also possible to function as a visible light sensor by overlaying a color filter on the light receiving region of the photosensor. In addition, in order to improve the photosensor light sensitivity, a large amount of incident light is taken in. Therefore, an opening is provided in the color filter in a region overlapping the light receiving region of the photosensor so that the light receiving region of the photosensor and the color filter do not overlap. It is good also as a structure.

This embodiment can be freely combined with Embodiment 1 or Embodiment 2.

(Embodiment 4)
In this embodiment, examples of electronic devices each including the liquid crystal display device described in the above embodiment will be described.

FIG. 10A illustrates an electronic book (also referred to as an E-book) which includes a housing 9630 and a display portion 963.
1, an operation key 9632, a solar battery 9633, and a charge / discharge control circuit 9634 can be provided. A solar cell 9633 and a display panel are attached so as to be freely openable and closable, and the electronic book supplies power from the solar cell to the display panel or the video signal processing unit. The electronic book illustrated in FIG. 10A has a function of displaying various information (still images, moving images, text images, and the like), a function of displaying a calendar, date, time, and the like on the display portion, and information displayed on the display portion. Touch input operation or editing, and a function of controlling processing by various software (programs). In FIG. 10A, as an example of the charge / discharge control circuit 9634, a battery 9635, a DCDC converter (hereinafter abbreviated as a converter 9636) are used.
It shows about the structure which has.

The display portion 9631 is a reflective liquid crystal display device having a touch input function using a photosensor, and is used in a relatively bright situation. Therefore, the display portion 9631 efficiently performs power generation using the solar cell 9633 and charging with the battery 9635. Can be preferred. Note that the solar cell 9633 is preferable because the battery 9635 can be efficiently charged on the front and back surfaces of the housing 9630. Note that as the battery 9635, when a lithium ion battery is used, there is an advantage that reduction in size can be achieved.

10B illustrates the structure and operation of the charge / discharge control circuit 9634 illustrated in FIG.
Will be described with reference to a block diagram. FIG. 10B illustrates a solar cell 9633, a battery 963, and the like.
5, converter 9636, converter 9637, switches SW1 to SW3, display unit 96
31, a battery 9635, a converter 9636, a converter 963
7. The switches SW1 to SW3 are locations corresponding to the charge / discharge control circuit 9634.

First, an example of operation in the case where power is generated by the solar battery 9633 using external light is described.
The power generated by the solar battery is boosted or lowered by the converter 9636 so that the voltage for charging the battery 9635 is obtained. In addition, the solar cell 9
When power from 633 is used, the switch SW1 is turned on, and the converter 9637 increases or decreases the voltage required for the display portion 9631. In addition, the display portion 9631
When the display is not performed, the battery SW 9635 is turned off and the battery SW 9635 is turned on.
The configuration may be such that charging is performed.

Note that although the solar cell 9633 is illustrated as an example of a charging unit, a configuration in which the battery 9635 is charged by another unit may be used. Moreover, it is good also as a structure performed combining another charging means.

This embodiment can be implemented in appropriate combination with the structures described in the other embodiments.

(Embodiment 5)
In this embodiment, after a transistor and a photosensor are formed over a glass substrate, the transistor and the photosensor are transferred and mounted over a flexible substrate. Note that here, cross-sectional process diagrams of a transistor are shown in FIGS. 13A, 13B, and 13C.
Detailed description of the steps and the structure of the photodiode and the like that are the same as those in Embodiment Mode 2 are omitted, and the same portions as those in FIGS. 8A and 8B are denoted by the same reference numerals.

First, the separation layer 260 is formed over the substrate 230 by a sputtering method, and an oxide insulating film 261 that functions as a base film is formed thereover. Note that a glass substrate, a quartz substrate, or the like is used as the substrate 230. The oxide insulating film 261 is formed using silicon oxide, silicon oxynitride (SiOxNy) (x>y> 0), silicon nitride oxide (S) by a PCVD method, a sputtering method, or the like.
It is formed using a material such as iNxOy) (x>y> 0).

For the peeling layer 260, a metal film, a stacked structure of a metal film and a metal oxide film, or the like can be used. As the metal film, tungsten (W), molybdenum (Mo), titanium (Ti), tantalum (Ta), niobium (Nb), nickel (Ni), cobalt (Co), zirconium (
Zr), zinc (Zn), ruthenium (Ru), rhodium (Rh), palladium (Pd),
A film made of an element selected from osmium (Os) and iridium (Ir) or an alloy material or a compound material containing the element as a main component is formed as a single layer or a stacked layer. For example, in the case where a tungsten film is provided as a metal film by a sputtering method, a CVD method, or the like, a metal oxide film made of tungsten oxide can be formed on the tungsten film surface by performing plasma treatment on the tungsten film. In addition, for example, a metal film (for example, tungsten)
After forming, an insulating film such as silicon oxide may be provided over the metal film by sputtering, and a metal oxide (for example, tungsten oxide over tungsten) may be formed over the metal film.
Further, as the plasma processing, for example, high density plasma processing using a high density plasma apparatus may be performed. In addition to the metal oxide film, a metal nitride film or a metal oxynitride film may be used. In this case, plasma treatment or heat treatment may be performed on the metal film in a nitrogen atmosphere or a nitrogen and oxygen atmosphere.

Next, after a conductive film is formed over the oxide insulating film 261, the gate signal line 227, the capacitor wiring 224, the photo film is formed by a first photolithography process using a first exposure mask as in Embodiment 2. A diode reset signal line, a readout signal line, and a photosensor reference signal line are formed.

In the subsequent steps, the transistor and the reflective electrode layer 242 are formed in accordance with Embodiment Mode 2.
Then, the reflective electrode layer 242 is covered with a water-soluble resin layer 262. A cross-sectional view at this stage is shown in FIG.
Shown in (A). Note that FIG. 13A illustrates a cross-sectional structure around the reflective electrode layer 242 for simplification, and does not illustrate a photodiode formed over the same substrate.

Next, after fixing the water-soluble resin layer 262 to a supporting substrate or the like, an opening is formed by irradiating the separation layer with laser light or the like, and the layer including the transistor is separated from the substrate 230. A cross-sectional view at this stage is illustrated in FIG. As shown in FIG. 13B, separation is performed at an interface between the separation layer 260 formed on the substrate 230 and the oxide insulating film 261.

Next, as illustrated in FIG. 13C, a flexible substrate 264 is attached to the surface of the layer including the transistor (the surface exposed by peeling) with an adhesive layer 263. Flexible substrate 2
As 64, a plastic film or a thin stainless steel substrate can be used.

Next, after removing the water-soluble resin layer 262, an alignment film 244 is formed. Then, the counter substrate 268 having the counter electrode 267 and the flexible substrate 264 are attached to each other using a sealant. Note that the alignment film 2 that covers the counter electrode 267 also on the counter substrate 268 before bonding is performed.
66 is formed. In the case of using a liquid crystal dropping method, liquid crystal is dropped in a region surrounded by a closed loop sealing material, and a pair of substrates is bonded under reduced pressure. Thus, the liquid crystal layer 265 is filled in a region surrounded by the pair of substrates and the sealant. The counter substrate 268 can be a flexible liquid crystal panel by using a plastic film with high translucency and low retardation.

In addition, the above-described example of manufacturing a flexible liquid crystal panel is only an example.
Alternatively, a flexible liquid crystal panel may be manufactured by thinly processing a glass substrate used as the counter substrate 268 by polishing or the like after the transistor is manufactured. In the case of thinning by polishing, after filling the liquid crystal layer, both the substrate 230 and the counter substrate 268 are polished and thinned.

FIG. 14 shows an example of an electronic book using a flexible liquid crystal panel.

FIG. 14 illustrates the case where a support portion 4308 is provided at one end of a liquid crystal panel 4311 as an example of an electronic book. Hereinafter, a specific configuration of the electronic book will be described with reference to FIG. Note that FIG. 14A illustrates a state in which the electronic book is placed sideways, and FIG. 14B illustrates a state in which the electronic book is set up.

An electronic book shown in FIG. 14 includes a flexible liquid crystal panel 4311 having a display portion 4301, a support portion 4308 provided at one end of the liquid crystal panel 4311, a scanning line driver circuit 4321a that performs display control of the display portion 4301, A photosensor driver circuit 4321b that controls a photodiode provided in the display portion 4301 and a signal line driver circuit 4323 that controls display of the display portion 4301 are provided.

The scan line driver circuit 4321a and the photosensor driver circuit 4321b are provided on a liquid crystal panel 4311.
The signal line driver circuit 4323 is provided in the support portion 4308.

The support portion 4308 is preferably configured to be more difficult to bend (higher rigidity) than at least the liquid crystal panel 4311. As an example, the housing constituting the support portion 4308 is attached to the liquid crystal panel 43.
11 or thicker than plastic or metal. In this case, the electronic book can be configured to bend (curve) at a portion other than the support portion 4308.

Further, the place where the support portion 4308 is provided is not particularly limited, but as an example, the liquid crystal panel 43 is provided.
A support portion 4308 can be provided along one end of 11. For example, as shown in FIG. 14, in the case where the liquid crystal panel 4311 has a rectangular shape, a support portion 4308 can be provided along a predetermined side (to fix one side). In addition, the rectangular shape here includes a case where corners are rounded.

In addition, the scan line driver circuit 4321a, the photo sensor driver circuit 4321b, and the display portion 430 are provided.
By forming the pixel circuit constituting 1 on a flexible substrate in the same process, the scan line driver circuit 4321a and the photosensor driver circuit 4321b can be curved and the cost can be reduced. it can.

The pixel circuit included in the display portion 4301, the scan line driver circuit 4321a, and the element included in the photosensor driver circuit 4321b can be formed using a thin film transistor or the like. On the other hand, a circuit that operates at high speed such as the signal line driver circuit 4323 is a semiconductor substrate such as silicon or SO.
An IC (Integrated Circuit) formed using the I substrate can be used, and the IC can be provided inside the support portion 4308.

The liquid crystal panel 4311 uses a flexible substrate and can input information without any problem because it is a touch input using a photodiode even when the screen is bent. The liquid crystal panel 4311 has better operability than other touch input methods.

Note that in this embodiment, an example in which a metal layer is used as the peeling layer is shown, but there is no particular limitation.
A peeling method using ablation by laser irradiation, a peeling method using an organic resin, or the like can be used.

(Embodiment 6)
In this embodiment, an example of a structure of a scan line driver circuit of a liquid crystal panel is described with reference to drawings.

FIG. 15 is a block diagram of a driver circuit described in this embodiment. V driver circuit
When used as a GA gate driver (scanning line driving circuit), since it is necessary to drive 480 gate lines, a data line for 9 bits is required. In the embodiment, an example of 3 bits will be described.

Block 701 is a circuit that generates a first-stage gate signal, block 702 is a circuit that generates a second-stage gate signal, block 703 is a circuit that generates a third-stage gate signal, and block 704 is a fourth-stage gate signal. A circuit for generating a gate signal, block 705 indicates a circuit for generating a fifth-stage gate signal. In the case of VGA, it continues to the 480th stage.

Data0a to Data2b indicate data lines. The second characters 0 to 2 from the end of the signal name correspond to 3 bits of data. The a and b at the end of the signal name are equivalent to an inverted signal of a, but b is not a completely inverted signal, and is 0 (low, GND) when there is no data input.
(Also called). The method of connecting the data line and the block of each stage is 00 in binary number in the first stage.
When expressed as 1, Data0a or Data0b corresponds to the least significant bit,
Since the least significant bit in the first row is 1, the last character is connected to b, that is, Data0b. Similarly, since the bit next to the least significant bit is 0, the last character is connected to Data1a having a.

FIG. 16 shows the time relationship of signals on each data line. Period 1 for selecting the first block 701
Corresponds to 001 in which 1 is a binary number, Data2a is 0 (low), Data1a is 0 (
Low), Data0a is set to 1 (high). In the period 2 for selecting the block 702 in the second stage, Data2a is set to 0 (low), Data1a is set to 1 (high), and Data0a is set to 0 (low) corresponding to 010 in which 2 is converted to a binary number. Data is determined in the same way for the third and subsequent stages.

When Data0a is 0 (low), the corresponding Data0b is set to 1 (high) of inverse logic,
When Data0a is 1 (high), Data0b is set to 0 (low). Data1b and Da
Similarly, ta2b has the reverse logic of Data1a and Data2a, respectively. However, between the period 1 for selecting the first block 701 and the period 2 for selecting the second block 702, Dat
A period in which both a0a and Data0b are 0 (low) is inserted, and a period in which no data is input is defined.

FIG. 17 is a circuit diagram constituting the inside of the block 701. Blocks 702, 703, 7
The same applies to the circuits constituting the inside of 04 and 705. In FIG. 17 as well, an example of 3 bits will be described. The N-type transistor group 802, the transistor 803, the transistor 804, and the transistor group 806 illustrated in FIG. 17 are formed over the same substrate as the transistor in the display portion, and use an oxide semiconductor layer as a channel.

Data0 in FIG. 15 corresponds to Data0 in FIG. 17, and Data0 in FIG.
Electrically connected to a0a or Data0b. The node 801 has a function of holding data. Although it may be held by a capacitor element, a parasitic capacitor may be used, and thus a capacitor element for holding is omitted in this embodiment. When one of the data lines Data0 to Data2 becomes 1 (high), one of the N-type transistor group 802 is turned on and the node 801 becomes 0 (low). When all of the data lines Data0 to Data2 are 0 (low), the node 801 holds 1 (high), and this block is considered to be selected. Further, during a period when there is no data input, the data lines Data0 to Data2 are all set to 0 (low), and all the transistor groups 802 are turned off.

In order to set the node 801 to 1 (high), the reset signal is set to 1 (high), so that the transistor 803 which is an N-type transistor is turned on. Note that even when the transistor 803 is turned on, the node 801 is not necessarily at the same potential as VDD because of the threshold value of the transistor 803. The period when the reset signal is 1 (high) and the data lines Data0 to D
By not overlapping the period in which any of ata2 becomes 1 (high), the power supply VDD to GND
Can be prevented from increasing.

When all the data lines are 0 (low) during a data input period, that is, when a block is selected, the node 801 holds 1 (high), and the transistor 804 which is an N-type transistor is turned on. Further, when this block is selected, the node 801 is connected to the power supply VDD or GN.
D is not electrically connected to D, and the write signal is changed from 0 (low) to 1 (high).
The potential of the node 801 rises due to capacitive coupling of the capacitor 805. Capacity 805
This circuit is called a bootstrap circuit.

The potential after the rise of the node 801 is preferably higher than a potential obtained by adding the threshold value of the transistor 804 to the maximum potential of the write signal. If the potential after the rise of the node 801 becomes higher than the maximum potential of the write signal plus the threshold value of the transistor 804, the capacitance 8
05 may be unnecessary or a parasitic capacitance may be sufficient.

When the potential after the rise of the node 801 is lower than the potential obtained by adding the threshold of the transistor 804 to the maximum potential of the write signal, the potential of the node Out does not rise to the maximum potential of the write signal, and writing to the pixel is in time. There is a possibility of disappearing. Node 801 is write
When the write signal is changed from 0 (low) to 1 (high) by being higher than the potential obtained by adding the threshold value of the transistor 804 to the maximum potential of the e signal, the node Out is also changed from 0 (low) to 1 (high). ). The node Out is connected to the gate line of the pixel. Then write
When the e signal is changed from 1 (high) to 0 (low), the node 8 is connected by capacitive coupling of the capacitor 805.
Although the potential of 01 falls, it is about the potential of VDD given by the reset signal, and the transistor 804 is not turned off. That is, since the potential of the node 801 is higher than the potential obtained by adding the threshold value of the transistor 804 to the 0 (low) level of the write signal, the node Out also becomes 0 (low).

When any of the data lines is 1 (high) during a data input period, that is, when a block is not selected, the node 801 is 0 (low) and the transistor 804 is turned off.

Even when the write signal is changed from 0 (low) to 1 (high), the potential of the node 801 is 0 (low) and the transistor 804 is off because the transistor group 802 is on. If the ability of the transistor group 802 to flow current is low, the potential of the node 801 rises due to capacitive coupling of the capacitor 805, so it is necessary to determine the ability of the transistor group 802 to flow current so that the change of the node Out is reduced.

Next, even if the write signal is changed from 1 (high) to 0 (low), the transistor group 802
Is on, the potential of the node 801 is 0 (low) and the transistor 804 is off. If the ability of the transistor group 802 to flow current is low, the potential of the node 801 drops due to capacitive coupling of the capacitor 805, so it is necessary to determine the ability of the transistor group 802 to flow current so that the change of the node Out is reduced.

If there is no transistor group 806, one of the data lines is 1 (high) during the data input period.
At this time, that is, when this block is not selected, the node Out is not electrically connected to the power source, and may be affected by the video signal. The potential at the node Out also changes due to capacitive coupling between the source electrode and the drain electrode of the transistor 804. Therefore, it is preferable that the node Out be fixed to 0 (low) while the transistor 804 is off.

FIG. 18 is a diagram showing the time and the potential of each node. The operation of the circuit diagram of FIG. 17 will be described again with reference to FIG.

In the period 901, the node 801 becomes 1 (high) by the reset signal. In the period 901, the transistor 804 is in an on state, but since the write signal is 0 (low), Ou
The potential of t is also 0 (low). The next period 902 is a period until the reset signal is set to 0 (low) and data input is started. By providing the period 902, it is desirable to prevent an increase in current from the power supply VDD to GND.

The next period 903 is a period necessary to input data and determine the potential of the node 801. Here, a case where Data0 to Data2 are all 0 (low) is shown. Next period 9
At the beginning of 04, the write signal becomes 1 (high), and the potential of the node 801 also rises. In the period 904, the potential of the node Out also becomes 1 (high).

In the next period 905, the write signal is set to 0 (low). Although the potential of the node 801 also drops, the potential of the node Out becomes 0 (low) because the transistor 804 is on. In the next period 906, the data input period ends, and in the next period 907, the reset signal is set to 1 (high) again, and the potential of the node 801 is set to 1 (high). The above is one horizontal period,
Repeat thereafter. Instead of the period 903, one of the data lines Data0 to Data2 is set to 1.
A case of becoming (high) is indicated by a period 908. In the period 908, the data lines Data0 to Data
When either 2 is set to 1 (high), the potential of the node 801 becomes 0 (low). If period 9
When the write signal becomes 1 (high) in the next period 909 before the potential of the node 801 is sufficiently low to turn off the transistor 804 so that the transistor 804 is turned off, the transistor group 8
If only 06 is used, the potential at the node Out cannot be fixed, and the potential at the node Out may temporarily increase. If the transistor 804 is turned off in the period 908, the node Out remains at 0 (low) even if the write signal is set to 1 (high) in the next period 909. Note that due to the parasitic capacitance between the source electrode and the drain electrode of the transistor 804, the potential of the node Out tends to rise temporarily even when the transistor 804 is off. The transistor group 806 needs to be adjusted so that the pixel transistor is not turned on. Since the gate line has a large load, the parasitic capacitance between the source electrode and the drain electrode is not a big problem.

In this embodiment mode, 1 (high) is described as a VDD potential, and 0 (low) is described as a GND potential. If the maximum potential of the write signal is set to a value lower than VDD, the bootstrap circuit becomes unnecessary, but it is not desirable to prepare two types of power supplies outside because the cost increases. This embodiment can be operated with one type of power source.

The structure of the driver circuit of the display device described in this embodiment can be implemented in combination with any of the structures described in other embodiments in this specification.

The structure of the driver circuit of the display device described in this embodiment mode is that when the write signal and each data signal line are set to 0 (low) and the reset signal is set to 1 (high), the gate lines of all the pixels are 0.
(Low). Unlike the case where the shift register circuit is used for a driver circuit of a display device, the gate lines of pixels in an arbitrary row can be set to 1 (high) in an arbitrary order.

This embodiment is an example of a decoder circuit included in the driver circuit, and is not limited to the structure of the driver circuit of the display device described in this embodiment.

100: display panel 101: pixel circuit 103: pixel 104: pixel 105: display element 106: photo sensor 107: display element driving circuit 108 on the signal line side: display element driving circuit 109 on the scanning line side 109: photo sensor readout circuit 110: Photosensor drive circuit 115: color filters 116a, 116b: FPC
120: display panel 125: display element 135 light 139: external light 190 liquid crystal display module 201 transistor 202 holding capacitor 203 liquid crystal element 204 photodiode 205 transistor 206 transistor 207 gate signal line 208 photodiode reset signal line 209 signal line 210 video data signal Line 211 Photosensor output signal line 212 Photosensor reference signal line 213 Gate signal line 214 Capacitor wiring 221 Transistor 222 Holding capacitor 223 Liquid crystal element 224 Capacitor wiring 227 Gate signal line 230 Substrate 231 Insulating layer 232 Gate insulating layer 233 Oxide semiconductor layer 234 Electrode layer 235 Electrode layer 236 Electrode layer 237 Insulating layer 238 p layer 239 i layer 240 n layer 241 insulating layer 242 reflective electrode layer 243 connection electrode layer 244 alignment film 245 recess 251 Electrode layer 253 Oxide semiconductor layer 254 Electrode layer 255 Oxide semiconductor layer 256 Oxide semiconductor layer 257 Electrode layer 258 Electrode layer 260 Release layer 261 Oxide insulating film 262 Resin layer 263 Adhesive layer 264 Substrate 265 Liquid crystal layer 266 Alignment film 267 Counter electrode 268 Counter substrate 701 Block 702 Block 703 Block 704 Block 705 Block 801 Node 802 Transistor group 803 Transistor 804 Transistor 805 Capacitor 806 Transistor group 901 Period 902 Period 903 Period 904 Period 905 Period 906 Period 907 Period 908 Period 909 Period 1030 Electronic equipment 1031 Button 1032 Display unit 1033 Area 1034 Switch 1035 Power switch 1036 Keyboard display switch 4301 Display unit 4308 Support unit 43 1 liquid crystal panel 4321a scan line driver circuit 4321b photosensor driver circuit 4323 the signal line driver circuit 9630 housing 9631 display unit 9632 operation keys 9633 solar cell 9634 charge and discharge control circuit 9635 battery 9636 Converter 9637 Converter

Claims (1)

An electronic device including a display unit having a touch input function,
A first transistor electrically connected to the reflective electrode on the flexible substrate;
A photo sensor,
The photosensor is
A photodiode;
A second transistor having a gate signal line electrically connected to the photodiode;
A third transistor;
One of a source and a drain of the second transistor is electrically connected to a photosensor reference signal line, and the other of the source and the drain is electrically connected to one of the source and the drain of the third transistor;
The other of the source and the drain of the third transistor is electrically connected to the photosensor output signal line;
The electronic device is characterized in that the oxide semiconductor layer of the third transistor overlaps with a readout signal line through a gate insulating layer, and the readout signal line overlaps with the reflective electrode .